BACKGROUND ART When breathing ambient air it is most desirable that the air should not contain injurious matter such as toxic chemicals or particulate material. Such matter can arise in city environment through which people are obliged to pass to reach their destinations. Hazardous breathing environments including particulate matter can be experienced when travelling underground such as by tube train or on foot. It is known for individuals in such circumstances to place a handkerchief or scarf across the face to provide for a degree of filtering of particulate material..

DISCLOSURE OF INVENTION According to the present invention there is provided a filtering device in the form of an integral structure of plastics material comprising a pair of wing elements linked by a U-shaped clip the clip providing for temporary mounting of the device on a nasal septum so as to locate a wing element within in each nostril; each wing element being made up of a central filter region with an outer edge having a profile conforming to a cross-section of the nostril; the outer edge of the element being flexible to provide for conformation of the outer edge with a nostril into which it is inserted. Typically the central filter region is foraminous with holes providing for the passage of air while tending in use to retain particulate matter of a predetermined size drawn into a nostril in which an element containing the central filter region is positioned.

According to a first preferred version of the present invention the clip is tinted or transparent so as to be virtually invisible once the clip has been located on a septum in a nose of a user.

The filtering device of the present invention is readily inserted into the nose for retention on the septum while providing for the nostrils of the user to be effectively closed by means of the wing elements which allow for the passage of air during breathing by the user but act to retain particulate material.

BRIEF DESCRIPTION OF DRAWINGS An exemplary embodiment of the present invention will now be described with reference to the accompanying drawing of a filtering device of which: Figure 1 is a view from beneath; Figure 2 is a front view; and Figure 3 shows diagrammatically the device of Figures 1 and 2 located in a nose of a user.

MODE FOR CARRYING OUT THE INVENTION Filtering device 11 is an integral unit of polypropylene and comprises a pair of wing elements 12,13 linked by a U-shaped clip 14. The clip 14 provides for temporary mounting of the device 11 on a nasal septum 15 (Figure 3) in a nose N so as to locate a wing element in each nostril (respectively nostrils 16,17). Hereafter only element 12 will be described in more detail since the element 13 is identical in function and is a mirror image of element 12.

Element 12 is made up of a central filter region 19 with an outer edge 20 having a profile conforming to a cross section of the nostril 16 in which it is located. The outer edge 20 is flexible to provide for close conformation of the outer edge 20 with the inside of nostril 16 Figure 3). Thus air drawn into nostril 16 is obliged to pass through foraminous central filter region 19. Typically the central filter region 19 has an array of holes each of a size allowing for the passage of air through the region 19 while retaining particulate matter above a predetermined size drawn into nostril 16.

The element 12 is readily moulded so as to provide for a relatively thick central filter region 19 and a thin outer edge 20 so as to ensure that the element once in position effectively blocks the nostril 16 in which it is located so that any air passing the element 12 necessarily passes through the filter region 19.

Typically a user will insert device 11 into the nose on entering an underground location such as a tube station. To avoid significant bypassing of the nose during breathing the user either keeps their mouth shut or uses a separate filtering means over the mouth. The amount of air drawn into the nose will be sufficient for non- energetic action by the user. Once the user has left the environment of concern the device is readily withdrawn and can be retained for subsequent hygienic disposal.

The device 11 is readily inserted into the nose in an unobtrusive manner and is not visually intrusive when in use. Effectively the elements are hidden within the nose and the clip can be tinted or transparent so as to be virtually invisible once the device has been located on the nose of a user.

INDUSTRIAL APPLICABILITY The device of the exemplary embodiment is made of polypropylene. Other plastics material can be used. It is also envisaged that as the devices are cheap and a number are readily carried in a dispenser then once used the device will be disposed of.

However there may be situations where a re-usable version is found desirable or appropriate and in such cases the device will be fabricated so that a reasonable cleaning process does not result in undue degradation.

The device of the exemplary embodiment is readily manufactured on a large scale very cheaply for sale at a range of outlets. A dispenser including several devices is readily acquired and carried by a user so that the user can readily select a device in approaching an area where ambient air is believed to contain particulate matter.